Ferrous alloy



Sept. 16, 1941 A. T. CAPE ET AL FERROUS ALLOY Filed Aug. 3, 1940 Y v x,%c. 5o--------------7---------- --7---- 28 (a x o 2 4 a a 10m.

INVENTORS.

y CHARLES V FBERSTER ARTHUR 7T CAPE ATTORNEYS.

Patented Sept. 16, 1941 FERROUS ALLOY Arthur '1. Cape, Santa Cruz,Calif., and Charles V.

Foerster, Canton, Ohio, assignors to Coast Metals, Inc., Canton, OhioApplication August 3, 1940, Serial No. 351,135

2 Claims.

This invention relates to ferrous alloys, but has reference moreparticularly to ferrous alloys which are especially adapted forhard-facing purposes and for utilization in the form of castings.

It is perhaps well-known that there are, in general, three types ofhard-facing metals, which, briefly, are the hard carbides, thenon-ferrous type, and the compounds of ferrous materials. In facing abase metal with the hard carbides, the retaining metal flows onto themetal to be faced and becomes welded to it, the carbides not beingmelted. This type of hard facing alloy is highly resistant to abrasionbut it cracks badly and rapidly under repeated impact, and,consequently, its service is limited. Non-ferrous types of hard facingalloys have a relatively good wear resistance, although not as good asthe carbides, but are decidedly tougher. The hardfacing alloys of theferrous type vary greatly and it can be said that the effectiveness ofthe material can generally be indicated by the market price thereof. Inother words, the cheaper the hard facing metals of the ferrous type are,the lower is their effectiveness. That is, these cheaper materials aretoo soft and they wear rapidly. On the other hand, the more expensivethe hard facing alloy of the ferrous type, the

greater tendency they have to be brittle, although they are reasonablyresistant to wear.

A primary object of the present invention is to provide ferrous alloysfor hard-facing and casting purposes which not only have a highresistance to wear and abrasion, but have high resistance, as well, toheavy and repeated impacts, that is to say, they possess high mechanicalstrength.

Another object of the invention is to provide ferrous alloys forhard-facing and casting purposes, which are resistant to chemicalcorrosion, to oxidation at high temperatures, and possessing strength athigh temperatures.

A further object of the invention is to provide ferrous alloys of thehard-facing type which also possesses the quality of being capable offorming a sound bond with the base metal.

A still further object of the invention is to provide ferrous alloys ofthe hard-facing type, which have a viscosity, in the molten condition,such as to permit exceedingly easy application of the alloys to the basemetal.

Other objects of the invention, together with some of the advantageousfeatures thereof, will appear from the following description of thepreferred and other embodiments of the invention. It is to beunderstood, however, that we do not limit ourselves to the embodimentsdescribed, since our invention, as defined in the appended claims, canbe embodied in a plurality and variety of forms.

clockwise direction, to the r-axis.

In order to more clearly visualize the invention, reference may be hadto the accompanying drawing, forming a part of the present application,and in which appears a graph containing a curve A, all points of whichhave as their abscissae percentage of nickel, and as their ordinatespercentages of chromium.

Referring more particularly to this graph, it

may be noted that the graph contains two sets -common origin (0), butthe arr-axis is inclined at an angle of degrees, measured in a counter-The :c-axis denotes percentages of nickel and the y-axis denotespercentages of chromium.

Curve A is a parabola, whose principal axis is the :ri-axis and whoseequation or formula is x1-cy1 =a, where a and c are constants, with11:2.7 and 0:0.9. To reduce this formula or equation to concentrationsof percentages of chromium and nickel, the following is established: V

m1cy1 must be greater than a, which equals 2.7, where and :0 equals thepercentage of nickel and 1!; equals the percentage of chromium. Theparabola defined in terms of concentration of chromium and nickel isplus .217y and g minus .4332;

2 plus .2171; minus c minus .433z) equals a The alloys of our inventionlie within the area designated No. 1 in the graph, this area beingbounded by the parabola A and the lines representing 10% nickel and 30%chromium.

The curve passes through points or values where there is a criticalchange of hardness from the austenitic to the ferritic or more magneticstate. The critical change in hardness from compositions within area No.1 to those lying outside this area is accompanied by changes in themagnetic values, from a value of 3 inside the curve to 4 just outsidethe curve, such values being arbitrary but reproducable. The method usedfor determining these arbitrary values consists in balancing the metalto be tested, bringing a magnet to a fixed point and noting thedeflection. Such a test readily designates the general physicalcharacteristics of an unknown chromium-nickel-composition or a knowncomposition to which other alloying elements have been added.

The alloys lying within area No. 1 are especially adapted forhard-facing applications, where softness from the point of view ofindentation hardness is of advantage, for resistance to impact. At thesame time, the complex chromium carbide plates distributed through thematrix in these alloys, plus the fact that the matrix itself isaustenitic, and therefore hardens as soon'as any work is done, impartsto this group a resistance to wear which is remarkable. In practice, wehave been able to lay down deposits as soft as 30 Rockwell C(approximately 290 Brinell) which are file hard. A preferred alloy ofthis group contains about 4.20% carbon, about 14%-18% chromium, andabout 4%-6% nickel. This alloy is particularly useful in the form ofweld rods for hard facing applications for cement mill machinery,agricultural equipment, brick, clay and tile machines, including mullertires; hammer mill parts, and coke handling equipment.

The alloys in area No. 1 preferably contain about 4% carbon, but maycontain from about 3% to about 5% carbon.

For hard-facing applications, where corrosion resistance, particularlyto hydrochloric acid is desired, copper in amounts of from about .2% toabout .5% is added to the aforesaid basic alloys. A preferred alloy ofthis type contains about 4% carbon, about 16% chromium, about 6% nickeland about 2% copper. Where edge strength and resistance to hightemperatures are required in addition to corrosion-resistance,molybdenum in amounts of from about .2% to about 2%, and phosphorus inamounts of from about .06% to about .2% may be added to the alloys. Apreferred alloy of this type contains about 4% carbon, about 16%chromium, about 6% nickel, about 2% copper, about 1% molybdenum andabout .10% phosphorus.

In manufacturing the aforesaid alloys, it is desirable to produce soundcastings or good welding material. For this purpose, the original chargein the furnace must be kept free from silicon, or as reasonably lowinsilicon as is possible, and also free from titanium. If theseconditions are not observed, the material, whether used in castings oras acetylene welding rods, is porous. For arc welding, these factors arenot quite as important, because the gases present in the welding rod areremoved during the arc welding process. In order to control theacetylene welding property of the material and also to some extent thearc welding characteristics, a small quantity of alkaline earth oralkali metal is added to the melt. The addition of minutely smallquantities of these elements increases the wetting properties of all ofthe varieties. Without them, during acetylene welding, the metal tendsto form into balls, the surface is improperly covered and the adherenceis not satisfactory. With an immeasurably small amount of sodium,potassium or calcium, the metal melted by the acetylene torch spreadsover the surface and covers it excellently. This is a most valuableproperty, and distinguishes the present alloys from all other weldingmaterials. The addition of calcium to the metal is preferably as calciumsilicide. The addition of these elements increases the fluidity of themetal, as well as merely changing the surface tension. The quantity ofcalcium silicide used is about .07 ounce per pound of metal. The amountused is well in excess of that required.

The arc welding rods are coated with a mixture of plumbago and sodiumsilicate, to which a small quantity of bentonite sometimes is added, orthey may be coated with a mixture of graphite (in the form of crushedarc furnace electrodes) and sodium silicate, to which bentonitesometimes is added. The use of these coatings is of considerableinterest. Where the rods are coated with plumbago, the deposits aresoft; where the rods are coated with graphite, the deposits are hard.Differences as great as 30 Rockwell C to 55 Rockwell C can be pro--duced by the selective use of these coatings. The normal mixturesemployed in these coatings are as follows, the rods being coated bysimply dipping them in the mixture and drying them:

This peculiar effect of plumbago as against graphite is of interest notonly in connection with the present alloys, but also in connection withthe coating of welding rods formed of other alloys and compositions.

It has been found that where the problem of porosity arises, theaddition of fluoride either to the metal itself in the case of castings,or as a thin layer over the graphite coating of the welding rod can beused effectively in eliminating the gas pockets. All of the fluoridesare effective in removing gases from the molten metal and in the eventof unduly humid conditions causing an absorption of the gases can beeliminated during the freezing process by the addition of the fluorideto the molten metal. In many cases where it is necessary to weld ondirty or gassy cast iron or cast steel the addition of fluoride eitherwith the graphite or plumbago coating, or as a thin layer superimposedupon the coating, will prevent porosity in the welded deposit.

The alloys should be kept as free from elements other than thosedescribed, as possible. In other words, silicon; manganese, phosphorusand sulphur should be kept to a minimum.

The alloys can be increased in hardness by heating them to 1650 F., andup and cooling them fairly slowly. This is a true precipitationhardening phenomenon.

We claim: 1. A ferrous alloy consisting of more than 3% but not morethan 5% carbon, nickel in amounts.

of from 1.7% to 10%, chromium in amounts of from 9% to 30%, copper inamounts of from .2% to about 5%, molybdenum in amounts of from .2% toabout 2%, phosphorus in amounts of from about .06% to .2%, the balanceof the ARTHUR r. CAPE. CHARLES v. FOERSTER.

